We plan to investigate epidemiologically both the maternal and fetal complications of maternal infection with C. trachomatis during pregnancy. We wish to determine whether amnionitis, premature rupture of membranes, and post-partum endometritis are associated with maternal chlamydial infection. In addition, amniotic fluid obtained at amniocentesis will be examined to directly identify intra-amniotic chlamydial infection during pregnancy. The association of chlamydia with amnionitis, premature rupture of membranes; postpartum endometritis, and spontaneous abortion will be estimated through case-control studies in which women with these conditions and control women are cultured for chlamydia and other genital tract pathogens. The prevalence of chlamydia in amniotic fluid will be compared to its prevalence in the cervix of the same women and to controls. To estimate the risk of chlamydial infection in pregnancy a prospective study on pregnant women is planned in which abnormal pregnancy outcomes (amnionitis, spontaneous abortion, fetal death, premature rupture of membranes, prematurity, post-partum endometritis) are compared in chlamydia-positive and chlamydia-negative women. Finally, to further clarify the role of chlamydia in positive women with infectious pregnancy complications (amnionitis or endometritis), a randomized treatment trial will be conducted in these women using standard therapy (clindamycin/gentamicin) versus standard therapy plus erythromycin. This work will elucidate the role of C. trachomatis in complications of pregnancy. Since chlamydial infection in treatable, early identification of high risk women, diagnosis and treatment could eliminate or reduce morbidity and mortality in those mothers and infants involved.